Braun tube



Feb. 25, 1936. s. LOEWE ET AL BRAUNTUBE Filed July 15, 1933 Patented Feb. 25, 1936 UNITED STATES PATENT OFFICE.

Application July-15, 1933, Serial No. 680,594

In Germany Jul! 20, 1932 I 3 Claims. (Cl. 250-275) In the case or highly evacuated discharge ves-- sels composed of fragile material such, for example, as glass it may occur, particularly if the vessels are of relatively large size or, as for example in the case of Braun tubes, possess an extended form, that the wall of the vessel does not withstand the outer pressure of the air and the vessels are caused to collapse, i. e., implode.

It has already been proposed to protect discharge vessels, in which this danger of implosion 1 exists, by fitting the same into suitable boxes composed of sheet metal or the like, or to surround the same with a wire structure.

According to the invention, vessels of this nature are furnished with an anti-implosion means, which is considerably more simple to produce, and which may also be employed in those cases in which the known protective means camnot be made use of either for electrical or for no optical reasons.

For this purpose the discharge vessel is furnished with an elastic and preferably firmly adhering preferably transparent coating.

A coating of this nature may, in accordance with the invention, consist of an elastic varnish of suitable composition, for example an artiflcal resin or the like, which may be applied by painting the same on, by immersion or by spraying on. The varnish may, if desired, contain an addition 30 of asbestos meal, fibres, paper pulp or the like.

The said additions may also be applied with the use of water-glass or the like as binding agent. In the same manner it is also possible to furnish the glass bulb with a rubber skin or a coating 35 composed of another plastic mass. A rubber coating of this nature may be produced by immersing the glass bulb in a rubber solution and if necessary vulcanizing the dried coating. on the other hand it is also possible to produce rub- 40 her caps or suitable shaped rubber coverings (for example rubber sleeves) separately, slip the same over the bulb, and if desired connect them firmly therewith by cementing or the like. In place of a coating composed of rubber there may also be 45 employed one composed of paper, silk or other sultablewoven materials, which may also be connected with the bulb by cementing or the like.

If the transparency of the bulb is to be maintained there are employed in accordance with.

50 the invention coatings composed of transparent material, preferably of transparent varnishes.

In those cases in which the vessels are greatly heated when in operation, and the resulting heat coating may either contain itself an addition of black substances, such for example as carbon or graphite, or be provided thereunder with a good heat-radiating coating. The bulb in this case is first furnished with a coating of good heatradiating material, to which there is then applied the actual anti-implosion coating.

The bottom of the Braun tube on the inner side of which a fluorescent substance is arranged according to the invention may be especially furnished with such transparent coating.

In the drawing there are shown by way of example two r'orms of embodiment of the discharge vessel according to the invention, in these Fig. 1 shows a bulb furnished with simple antiimplosion means, according to the invention, whilst in Fig. 2 there is provided between the wall of the bulb and the protective coating 9. further good heat-radiating coating.

In the drawing l is the discharge vessel having the glass wall 2, the protective coating 3 consisting of varnish or one of the substances referred to above, and 4 the heat-radiating layer interposed between the glass wall and the protective layer.

Discharge vessels which are furnished with the anti-implosion means according to the invention are subject to a much smaller extent to the danger of implosion than the vessels hitherto known, since on the one hand, by reason of the anti-implosion layer, the powers of resistance of the vessel are considerably increased, and because the vessel on the other hand, even should implosion take place, collapses without the possibility of small fragments resulting in large number. The protective effect of the anti-implosion layer is based in particular on the fact that damage to the surface of the glass wall such as may otherwise occur even upon the slightest blow, and lead subsequently to implosion, is safely avoided by reason of the elastic layer.

We claim:

1. A Braun tube including an evacuated bulb having a bottom furnished at its inside with a coating of fluorescent material, the side walls of the bulb being furnished at their outside with a coating of good heat radiating material and with a further elastic, firmly adhering coating of transparent material, said further coating being arranged on the first said coating for the purpose of preventing an implosion of the bulb.

2. A Braun tube including an evacuated bulb having a bottom furnished at its inside with a coating of fluorescent material, the side walls of laid bulb being furnished at their outside with an elastic, firmly adhering coating consisting oi rub-.

bet for the purpose of pneventing I'm implosion o! the bulb, the bottom of the Drum tube being furnished at its outside with a. coating of trans pu'ent material. i

8.Aflnuntubeincludinganevmuatedlmlb hamlbottommmlshedatitlinldeflthl. 

